Fuse



Nov. 8, 1938 T. BlRKENMAlER o FUSE Filed Dec. 24/ 1957 2 Sheets-Sheet 2 Patented Nov. 8,1938

' UNITED STATES FUSE Theodore Birkenmaier, St. Louis, Mo., assignor to W. N. Matthews Corporation, St. Louis, Mo., a

corporation of Missouri Application December 24, 1937, Serial No. 181,585

8 Claims.

This invention relates to fuses, and with regard to certain more specific features, to expulsion fuses.

The invention is an improvement upon the structure shown in my Patent No. 2,077,207 for Fuse, dated April13, 1937.

Among'the several objects of the invention may be noted the provision of a fuse such as shown in said patent wherein an inside, instead of an outside tube slides downwardly to effect the operation; the provision of apparatus of the class described which permits the advantages of the construction shown in said patent to be used in connection with the so-calied knife contacts, as well as with the latch-type ofcontacts shown in said patent; the provision of apparatus of this class which is adapted to drop the fuse lirik after withdrawing the same from the expulsion tube; and. the provision of apparatus of the class in which a door shall remain in place more effectively. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter 1 described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings in which is illustrated one of various possible embodiments of the invention- Fig. 1 is a vertical section of a fuse box incorporating the invention; J

r Fig. 2 is a front elevation of Fig. 1;

Fig. 3 is a bottom plan view of Fig. 1;

Fig. 4 is a view similar to Fig. 1 showing an alternative relationship of parts after blowing of a fuse;

Fig. 51s a fragmentary rear elevation of a clamping mechanism; and, Fig. 6 is a bottom view of the parts shown in Fig.5. w

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

In some instances, it is desirable that the structure disclosed in my Patent 2,077,207, be used in connection with so-called-knife contacts; that is, with contacts in which the termina1-engag-.

5 ing portions on the fuse are springingly held between sideward spring clips. The solution of the problem of the application of said structure to such contacts is, among other things, herein given.

55 Referring now more particularly to Fig. 1,

there is shown at numeral l a fuse box having an open bottom 2. The box includes a septum 8i notched at 83 for accommodating a tube 29 to be described. The box also has a pivot pin 3 for the hook-shaped portion 5 of a door I, the 5 latter carrying an eye '9 for manipulating the same to open and closed positions. In open position, the door may be entirely separated from the box by unhooking the hook from the pivot pin 3. In closed position, the pin 3 and the 10 hook are inseparable. The box I and the door 1 are composed of insulating material, such as porcelain and Bakelite" respectively.

The door of the present box is improved over that shown in said patent by providing later- 15 ally extending lugs II which swing down, into position below the extensions l3 of the box when the door is swung down (see Fig. 4). Thus, if while depending, a iinemans tool or the like strikes the door and tends to force it upwardly, 20 it cannot be pushed up high enough to unlatch. However, it may be unlatched when ator near the dotted-line position B as shown in Fig. 1. It cannot be unlatched when in the dotted line position A shown in Fig. 4. Neither can it be 25 unlatched in the solid-line position shown either in Figures 1 or 4. 3

0n the door 1 is an upper support Hand a lower support ll, these being respectively integrally associated with terminal engaging eie- 30.

ments l9 and 2|. These terminal engaging'elements have flat sides for engagement with the flat sides of spring line terminals 23 and 25, the latter being held fastened to the box I. These line terminals 23 and 25 have wire-receiving clamping yokes 2'! for the usual wire-holding pu p s s. l

From the above it will be seen that the contact between the terminal engagingeiements l9 and 2| and the line terminals 23 and 25.are of 40 the so-called knife-contact variety which ordinarily would substantially resist any vertical motion and which consequently would resist the easy sliding down of theoutside tube such as 43 of Patent 2,077, 07.

In order thatI may use the sliding tube arrangement of said patent, the terminal engaging elements I! and 2| are joined'by means of an outer insulating tube 2! or its equivalent. The

' tube ll is'threaded into the upper terminal en- 5 gaging element ",andis held to the lower engaging element 2| by means of a set screw or the like. I

The upper terminal engaging element IS includes an opening 3| through which may be in- 56 serted, first the flexible lower length 33 of a fuse iink and then a fusible portion 35 and an upper flexible portion 31. The opening 3| will not admit the attached head as. The head as is clamped by means of a cap 4|.

I'he fuse link, which I will hereinafter designate in general by the letter F is positioned within an inner insulating tube 43. This tube at its upper end slidably fits into a socket 45 in the terminal engaging element I9. The tube 43 passes downwardly through the outer. tube. 29 and extends a slight distance from the lower end thereof. At its lower end it is provided with a sideward notch 47 throughout which laterally passes the lower end of the fuse link F.

An outside ring 48 fastened on the inner tube 43 is adapted to drop down and rest upon an inner ring fastened to the inside of the fixed outer tube 29. Thus the inner tube has a limited downward motion such as illustrated in Fig. 4. This tube is free of any contact with the line terminals 23 or 25, and consequently there is no friction therewith.

To hold the lower end of the fuse link F, there is provided on the lower terminal engaging element 2! a rearward conducting clevis 53. Pivoted to this clevis-53 is a downwardly extending arm 55 of conducting material which passes through a bridge 51. The bridge constitutes a means for limitingthe outward swing of the link 55. A spring 65 forces the arm 55 against the bridge (Fig.4)h' i The link 55 reaches downwardly to a point whereitlin turnis formed as a clevis 59 between the fingers of which is pivoted a clamping lever 6|. Thelever'fil is normally forced by a spring 53in a-clockwise direction (Fig. 4).; I'he clockwise'm'ovement is limited by the action of a pin H which extends from the link 6| and engages theunders'ide of finger 61 of said clevis 59.

In view of 'the' above it will be clear that since the lever-55 is limited in its clockwise motion by the-bridge (Fig. 4), and the lever 6| is limited in its clockwise motion on lever 55 that the two levers-assume a' free position such as shown in Fig. 4 when the fuse link is not applied thereto.

a Provisionismade for applying the fuse link at its lower -"end toisaid levers as follows:

The loweriend 'of the lever Si is formed with a lateral-finger '13 (Figures 5 and 6) over which J thelower nend ot the fuse link is placed. The fuse link endis then passed beneat a lateral clamping-portion? on lever SI and, over a seat portionl 'l'on' the finger 61 of lever 55.

I *When-the f-use is placed in the position shown in Figures 1, 3, 5 and 6, it is pulled enough so --z=that there is-afiendency to move the lower lever 6|:counteredlockwise (see Fig. 1). This causes i". its clamp. to clamp the fuse link F against the mspringtiin Hence, under the tension-of spring 65,

seatirlfli r Further pull draws the lever 55 against the;levers 55- and H, are maintained in clamping Ythefuselinkinqresponse to tension in the spring positions ,asj.;shown in Fig. 1. Hence there is effected automatic clamping of thelower end of thetube.; .43, the lower end being relatively flexiblegtorg; in .thecase of a very heavy fuse link. at i least .tohold the link in a position to prevent the descent of .the inner tube 43.

. -When; the fuse link melts at the fusible section 35, the tension in spring 65 is released so that the leveriiis'zpushedclockwise to effect a withdrawal -31? .,.;of-;. the=fuse11link. The expulsion action in the tube 43 aids the effect and ultimately the lower -Thentfiudency is to tension the fuse link in ".auxiliary to the tube for tensioning said fuse link prior to blowing and to aid in withdrawing end of the fuse link is projected downwardly. The fuse link which has descended from the inner tube 43 has no longer any action on the pin 73 to make the lever 5| effective as a clamp on the end of the fuse link; Thus the lever 6| swings clockwise on the link 55 to open clamp 75, thus releasing the fuse link which drops away from the box.

Next, the inner tube 43 slides down until the ring 49 rests on ring 5|, as shown in Fig. 4. The tube 43 extending from box I then functions as a telltale. The tube 43 acts as a telltale to show that the fuse is blown, even though no fuse link is hanging therefrom. Thus not only is the invention of my former Patent 2,077,207 made applicable to knife contact switch structures but at the same time, I effect the advantage of having the major parts of thefuse link drop from the apparatus after it is melted, thus avoiding short circuiting with adjacent wires.

To reload the device, it is only necessary to bring the door 1 into the position B and remove it. The fuse cartridge being thereon may then be handled as follows:

The cap 4| is removed and a fresh fuse link fed through the openings thus presented. The cap 4| is then replaced to clamp the head 39. The tube 43 at this time is again pushed up into the position shown in Fig. l, and the lower end of the link is brought out from the bottom of the tube through the notchv 41. The lower end of the link is then positioned over the fingers l3 and in between the clamping or holding portions 15 and 71. The fuse link is pulled taut and the lever 55 is thrown to the position shown in Fig. 1. Then, upon release of the lever, the spring 65 tensions the levers 55 and BI as described.

It will be understood that although the door 1 is shown as being hinged to the box I, that it may be otherwise movably supported as by permitting the line terminals 23 and 25 to support the door assembly through the frictional engagement with the terminal engaging elements l9 and 2|.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in carrying out the'above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim: 1 v

1. In apparatus of the class described, a base, spaced line terminals thereon, a movable member associated with the base, terminal engaging elements on the movable member cooperable with said line terminals, a fuse tube, means for slidably arranging said tube with respect to said terminal engaging elements, the tube being free of any enthe lower portion after the link has blown.

. 2. In apparatus of the class described, a base, spaced line terminals thereon, a movablemember associated with the base, terminal engaging elements on the movable member cooperable with said line terminals, a fuse tube, means for slidably arranging said tube with respect to said terminal engaging elements, the tube being free of any engagement with the line terminals, a fuse link joining said terminal engaging elements and passing through said slidable tube, and means auxiliary to the tube for tensioning said fuse link prior to blowing to aid in withdrawing the lower portion after the link has blown, said slidable tube.

being supported by the fuse link while the latter is tensioned.

- said slidable tube, means auxiliary to the tube for link has blown, said tensioning means being tensioning said fuse link prior to blowing to aid in its withdrawing the lower portion after the adapted to drop the withdrawn portion of link after withdrawal from said tube.

4. In apparatus of the class described, a base, spaced line terminals thereon, a hinged member on the base, terminal engaging elements on the hinged member cooperable with said line terminals, a fuse tube, an outer stationary tubular member rigidly joining said terminal engaging elements, a slidable expulsion tube within said outer tube, a fuse link joining saidterminal engaging elements and passing through said expulsion tube and out. of the lower end thereof, said fuse when in conducted position supporting said expulsion tube and releasing said expulsion tube when the fuse blows, means for limiting the descent of the expulsion tube with respect to said stationary tube and means auxiliary to the tubefor tensioning said fuse link prior to blowing for within said outer member, a fuse link joining said terminal engaging elements and passing through said expulsion tube and out of the lower end thereof, said fuse when in conducted position supporting said expulsion tubeand releasing said expulsiontube when the fuse blows, means for limiting the descent of the expulsion tube with respect to said stationary member, means auxilimy to the tube for tensioning said fuse link prior to blowing for withdrawal of the same upon blowing, said tensioning means being adapted subsequently to drop the withdrawn portioniof the link tocompletely separate it from the apparatus.

6. In apparatus of the class described, a box, a door hinged to said box at the lower end, said box having an opening in the bottom, line terminals of the knife-contact variety in the box, terminal engaging elements on the door for engaging said line terminals, a movable tube located between said terminal engaging elements and having an open bottom, a fuse link joining said terminal engaging elements and passing through said movable tube and means auxiliary to the tube for tensioning said link prior to blowing to aid in withdrawing it as the fuse link blows, said movable tube being adapted to descend upon withdrawal of the link.

'7. In apparatus of the class described, a box, a door hinged to said box at the lower end, said box having an opening in the bottom, line terminals of r the knife-contact variety in the box, terminal engaging elements on the door for engageme'nt with said line terminals, a movable tube having a bottom opening located between said terminal engaging elements, a fuse link joining said terminal engaging elements and passing 'through said movable tube and passing out of its lower end, means for tensioning said link to aid in withdrawing it when the fuselink blows, said movable tube being adapted to descend upon withdrawal of the link and means for limiting the descent of the tube.

In apparatus of the class described, a box. a door hinged to said box at the lower end, said box having an opening in the bottom, line terminals of the knife-contact variety in the box, terminal engaging elements on the door for engaging said line terminals, a sliding tube located between said terminal engaging elements, a fuse link joining said terminal engaging elements and passing through said slidable tube, means auxiliary to the tube for tensioning said link to aid in withdrawing it when the fuse link blows, said sliding tube being adapted to descend upon withdrawal of the link, said tensioning means being adapted to drop said link after withdrawal thereof and means for limiting the descent of the tube. 

